There are many devices patented and otherwise which are designed to improve the golfer's swing whereby he overcomes the problems of hooking or slicing the ball and consequently improves his game. A popular form of swing training aid is a light located on the golf club head or adjacent the head on the hosel which traces an arc of light as the club is swung to impart a mental image to the golfer of the precise path of travel of the golf club head.
The following patents represent a selective sample taken from a large number of prior art patents disclosing similar devices and are represented to be only a sample. U.S. Pat. No. 3,070,373 issued to Donald K. Mathews et al discloses a light source attached to the golf club hosel projecting a collimated pencil beam of light downwardly onto the ground just ahead of the club and between the golfer and golf ball so that a visually perceived trace of club travel is given so that golfer and or instructor are informed of the correctness, or lack thereof, of the golfer's swing. The device is powered by a large battery pack resting on the ground. Two lights attached to the top of the club and arranged on a line at 90.degree. to the club face are disclosed in U.S. Pat. No. 3,191,939. The visual image conveyed during the swing comprises two arcs defined by the paths of the two lights which, if the paths coincide at the moment of impact of club against ball, indicate a proper stroke. If the paths diverge, a hook or slice and the amount thereof is indicated.
U.S. Pat. No. 3,677,553 issued to Eric D. Moore and U.S. Pat. No. 3,820,795 issued to David L. Taylor disclose club head lights indicating the golfer's swing, the latter further disclosing a battery for the light mounted within the golf club shaft. The use of ultraviolet light and luminescent strips on the golf club head or chemical light on the club head is disclosed in U.S. Pat. No. 3,649,028 issued to Eugene N. Worrell.
The prior art does not disclose a laser beam light source and convex mirror arrangement for projecting a fan of light forwardly of the club face to display a line on the ground just before, at the moment of impact, golf club and ball, and slightly afterwards to impart a substantially instantaneous visual impression of correctness or deviation of stroke. Thus, the present invention departs from the prior art methodology of relying on the stroboscopic effect of moving light and the persistence thereof in the mind of the viewer for analyzing the golfer's swing.